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Sept. 19, 2011 -- Giving premature baby girls formula supplemented with a certain type of fatty acid might lead to better reading and spelling skills at age 10, suggests a small study.

In addition, among children fed only formula and no breast milk as babies, those who received supplemented formula did a little better on some tests of mental ability at age 10.

Overall or in boys alone, though, the researchers did not find any long-term cognitive benefit from giving preterm babies formula supplemented with long-chain polyunsaturated fatty acid.

The researchers had randomly assigned 107 babies to receive either the supplemented formula or unsupplemented formula. No previously published study had examined the effect of supplemented formula in children as old as 10.

Many infant formulas now contain long-chain polyunsaturated fatty acids called DHA and ARA. Such fatty acids are found in breast milk but not in conventional infant formulas.

Those fatty acids play an important role in the growth of new brain white matter during the first year of life.

But studies about the benefits of supplemented formulas on brain development have been inconclusive, Tonse Raju, MD, a medical officer in the pregnancy and perinatology branch at the National Institutes of Health, tells WebMD. Raju, who was not involved with the latest research, served on the steering committee for The Surgeon General’s Call to Action to Support Breastfeeding, released in January.

“There is no doubt that the existing literature indicates that the effects (when they are demonstrated) tend to be greater in preterm than term infants,” study researcher Elizabeth Isaacs, PhD, a neuropsychologist and cognitive neuroscientist at the University College London Institute of Child Health, said in an email.

Much research, though, has found that babies who are exclusively breastfed have higher IQs than those who are not, Raju says.

Breastfeeding and Mental Development

A companion study suggests that the long-chain polyunsaturated fatty acids in breast milk deserve credit for that. The Spanish study followed women during pregnancy and their children from birth through 14 months. The researchers collected information about a variety of factors that could affect children’s mental development, including the mothers’ IQ, education, social class, and level of attachment to their children.

But scientists found that how much the babies had been breastfed -- largely independent from those psychosocial factors -- was related to higher mental development at 14 months.

The researchers also measured levels of long-chain polyunsaturated fatty acids in the colostrum of new mothers. Colostrum is a form of breast milk that is produced in the first few days after giving birth. It was found that high levels of these fatty acids in colostrum were associated with benefit in mental development in infants receiving a large amount of breast milk.

Because it’s impossible to randomly assign babies to exclusively breast milk or formula, though, Raju says, the Spanish researchers might have overlooked some other characteristic that distinguished the moms who mainly breastfed from those who didn’t.

Even if breast milk did account for the difference in mental development, the key ingredient might not have been the fatty acids, Isaacs says. Perhaps, she says, it’s cholesterol, which is not found in formula and does play an essential role in the nervous system.

About three out of four new mothers are breastfeeding when they leave the hospital after delivery, Raju says. Often, the need to return to work cuts breastfeeding short, he says, but even exclusively breastfeeding for a month is beneficial.